We are working on a new description of color discrimination that used information transfer analysis. Psychophysical results have been obtained on the minimum detectable chromatic contrast between pairs of wavelengths throughout the visible spectrum. These psychophysical results will now be compared with the results of recording the electroretinogram (ERG) and the visually evoked cortical potentials (VECP) arising from phase alternation in sinusoidal gratings composed of the same wavelength pairs. This extends and generalizes the ERG research carried out on human and pigeon eyes and earlier human VECP results. The data of all these experiments yield sets of "chromaticity functions" that display chromatic differences in diagrammatic form.